This sequence of videos leads students through activities to help them answer the question, “Why is my shadow shorter sometimes and longer other times?” In the introductory video, the materials are described. In the first video directed towards students, students share their initial ideas about the question. In subsequent videos, students make and record observations of shadows, develop and use a model to figure out the Sun’s apparent daily pattern of motion in the sky, and check the accuracy of their model by observing photographs of the Sun. At the end, students explain why their shadow is shorter sometimes and longer other times.